Takahashi Yoshio, Sakuma Kyoko, Itai Takaaki, Zheng Guodong, Mitsunobu Satoshi
Department of Earth and Planetary Systems Science, Hiroshima University Hiroshima 739-8526, Japan.
Environ Sci Technol. 2008 Dec 15;42(24):9045-50. doi: 10.1021/es802073x.
The oxidation state and coordination environment of antimony (Sb) incorporated into polyethylene terephthalate (PET) bottles were estimated based on X-ray absorption fine structure (XAFS) at Sb K-edge. Prior to XAFS analyses, Sb concentrations in 177 PET bottles collected in Japan and China were determined, showing that 30.5% and 100% of Japanese and Chinese PET bottles, respectively, contained more than 10 mg/kg of Sb. Most of the bottles used for aseptic cold filling and carbonated drinks contained a larger amount of Sb. Extended X-ray absorption fine structure (EXAFS) showed that the first neighboring atom of Sb in PET was estimated to be oxygen with a coordination number of about three. In addition, the contribution of Sb to Sb shell was discounted in the EXAFS, showing that Sb was not present as Sb2O3 in PET, although Sb was initially added as Sb2O3 in the production of PET. This information is consistent with the coordination environment estimated from the polycondensation reaction catalyzed by Sb, where Sb can be present as either Sb glycolate or Sb glycolate binding to the end group of the PET polymer. X-ray absorption near-edge structure (XANES) showed that Sb(III) initially added as Sb2O3 into PET was partially oxidized and the Sb(V) fractions reached approximately 50% in some samples. However, the oxidation state and coordination environment of Sb in PET had no relationship with the concentrations of Sb that leached into water from PET. Based on the present XAFS results and previous studies on the effects of temperature and others, it was concluded that the leaching behavior of Sb into water is primarily due to the degradation of PET itself, but is not related to the Sb species in the PET bottles.
基于锑（Sb）K边的X射线吸收精细结构（XAFS），对掺入聚对苯二甲酸乙二酯（PET）瓶中的锑（Sb）的氧化态和配位环境进行了估算。在进行XAFS分析之前，测定了在日本和中国收集的177个PET瓶中的Sb浓度，结果表明，日本和中国的PET瓶中分别有30.5%和100%含有超过10 mg/kg的Sb。大多数用于无菌冷灌装和碳酸饮料的瓶子含有较多的Sb。扩展X射线吸收精细结构（EXAFS）表明，PET中Sb的第一近邻原子估计为氧，配位数约为3。此外，在EXAFS中扣除了Sb对Sb壳层的贡献，表明尽管在PET生产中最初添加的是Sb2O3，但Sb在PET中并非以Sb2O3的形式存在。该信息与由Sb催化的缩聚反应估计的配位环境一致，其中Sb可以以乙醇酸锑或与PET聚合物端基结合的乙醇酸锑的形式存在。X射线吸收近边结构（XANES）表明，最初作为Sb2O3添加到PET中的Sb（III）部分被氧化，在一些样品中Sb（V）的比例达到约50%。然而，PET中Sb的氧化态和配位环境与从PET中浸出到水中的Sb浓度无关。基于目前的XAFS结果和先前关于温度等影响的研究，得出结论：Sb向水中的浸出行为主要是由于PET本身的降解，但与PET瓶中的Sb物种无关。
